High-density and hetero-functional group engineering of segmented hyperbranched polymers via click chemistry

A new kind of segmented hyperbranched polymers (SHPs), hyperbranched poly(glycidyl methacrylate)s (HPGMAs), were synthesized via reversible addition-fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP). HPGMAs were efficiently functionalized on the whole scaffold via a collection of click chemistries, including the azidation of oxirane, thiol-epoxy click chemistry, thiol-ene click chemistry, copper-catalyzed azide-alkyne cycloaddition (CuAAC), and Menschutkin chemistry, affording SHPs with hetero-functional groups including hydroxyl + azide, dual hydroxyl, triple hydroxyl, hydroxyl + tertiary amine, hydroxyl + alkene, hydroxyl + carboxyl, alkene + azide, alkyne + azide, hydroxyl + alkyne, dual hydroxyl + alkene etc., all at similar to 100% conversion. Thiol-epoxy + thiol-ene sequential dual click and thiol-epoxy + Menschutkin chemistry + CuAAC triple click strategies were presented, making functional group transformation readily accessible. Hydrophilic dendritic brushes, hydrophobic dendritic brushes and amphiphilic dendritic hetero-brushes were synthesized. Esterification of SHP containing hydroxy and azido groups with 1-pyrenebutyric acid yielded clickable fluorescent macromolecules, which showed a very strong excimer emission.